Mercado began her literary career in 1979; as such, some consider her to be part of the second wave of writers that constitute the Nuyorican literary movement. Of her work, Dr. Marilyn Kiss writes, "if the personal is political, then such verses as, "He was forgotten/before he could be remembered/by the heads of state/he provided sugar for," written about her grandfather, Don Portolo, "Director of the Sugar Cane Field Workers", and "Milla can speak of/The turn of the century land reforms,/Of the blinded enthusiasm/For a man called Marín..." about her grandmother, Milla, and "Juanita, Providing food from soil,/Creating homes from ashes,/Teaching tolerance by living..." about her aunt in Puerto Rico, offer testimony to the power of this type of poetic vision."[3]

Mercado's book of poems; It Concerns the Madness (Long Shot Productions), was published in 2000.[4] In 2005 she served on the editorial board for a special issue of Letras Femeninas; a publication of the Asociación Internacional De Literatura Femenina Hispánica, Department of Languages and Literature, Arizona State University.[5]Latino Leaders Magazine's 2007 issue profiled her as "one of the most celebrated members of the Puerto Rican literary movement in the Big Apple."[6]

^Mercado, Nancy. "Rooms for the Living: New York Poems." PhD diss., State University of New York at Binghamton, 2004. Listed in ProQuest Dissertations & Theses, retrieved May 19, 2012. ProQuest document ID 305071933.